FELINE HERPES VIRUS

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FELINE HERPES VIRUS

• Carol Szymanski, DVM, Dip. ACVO

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KEY POINTS

• Feline herpes virus (FHV) is the most common
  cause of acute keratoconjunctivitis
• Inherent difficulties in laboratory confirmation.
  Diagnosis based upon clinical features and
  response to therapy
• Lifelong latency in 80 of cats. Virus will
  spontaneously reactivate when cat stressed
• No single therapeutic regimen is consistently
  effective

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FELINE HERPES VIRUS

• Conjunctivitis
• Corneal Ulcers
• dendritic
• geographic
• Symblepharon
• Eosinophillic Keratitis
• Corneal Sequestrum /-

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CAT CONJUNCTIVITIS

• Usually of infectious origin
• Feline Herpes virus very common
• Chlamydia
• Mycoplasma, calicivirus-insignificant ocular
  pathogens

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TREATMENT

• Conjunctivitis without corneal ulceration
• Topical erythromycin, terramycin, gentamicin, or
  fluorquinalones are suitable.
• Neomycin in triple antibiotic may irritate.
• Chronic, non-responsive
• Azithromycin(Zithromax) 40mg SID x 14 days
• Doxycycline 5mg/kg BID x 21 days

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ULCERS SECONDARY TO HERPES VIRUS

• CLASSICDENDRITIC
• Superficial linear or branching

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ULCERS SECONDARY TO HERPES VIRUS

• GEOGRAPHIC, large, superficial
• Secondary bacterial infection may progress to
  deep ulcers or perforation

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Diagnosis

• PCR of limited value due to high incidence of
  false negative results
• Diagnosis is based on clinical appearance,
  history and response to therapy
• Underlying systemic disease can predispose cats
  to chronic ocular infections (FIV,FeLV)

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TOPICAL ANTIVIRALS

• Idoxuridine 0.5 ointment
• Vidarabine arabinoside 3 ointment
• Trifluridine 1 solution (most expensive and most
  irritating)
• Available from compounding pharmacies

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SYSTEMIC ANTIVIRALS

• ? Efficacy, concern about side effects
• Acyclovir 25mg/kg TID x 10 days
• Famcyclovir 125mg tabs ¼ tab BID x 10 days

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ADJUNCTIVE THERAPY

• L-lysine orally 250mg SID 500mg BID
• reduces viral replication and viral shedding
• decreases severity of ocular symptoms
• most effective when used early
• Interferon alpha-2b (Intron-A, Shering)
• 30 IU oral SID x 7 days, off 7 days, alternate
• prevents healthy cells from becoming infected

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SYMBLEPHARON

• Adhesion of any portion of the conjunctiva to
  itself or to the cornea.
• Young cats, following severe herpetic
  conjunctivitis.
• Extensive symblepharon difficult to treat
  surgically

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SYMBLEPHARON
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EOSINOPHILIC KERATITIS

• Immune mediated sequella to FHV.
• Adult cats
• Multifocal white plaques, corneal masses
• Cytology eosinophils, mast cells
• Steroid-responsive
• Requires long-term treatmenttaper slowly to
  prevent recurrence

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EOSINOPHILIC KERATITIS
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CORNEAL SEQUESTRUM

• Brown-black corneal stromal degeneration
• FHV infection and/or physiological exophthalmos
  in Persian Himalayan or Burmese cats
• Treatment of choice is surgical removal of
  degenerated cornea
• If lesion is small, superficial, treat with
  lubricant or antibiotic OO and sequestrum may
  slough
• Corticosteroids contraindicated

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CORNEAL SEQUESTRUM
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SUMMARY

• Repetitive eye infections are a frustrating
  clinical problem.
• The role of feline herpes virus is undisputed.
• No cure, but individual selection of medication
  will yield improvement in the majority of cases.
• Avoid steroids (except EOS keratitis).
• Client education essential.
• Reduce patients stress whenever possible.